A conventional pool cleaner comprises a base plate on which are mounted a pump, at least one motor for driving the pump and optionally a second motor for propelling the apparatus via wheels, rollers or endless track belts; a housing having a top and depending sidewalls and end walls that encloses the pump and motor(s) that are secured to the interior structure and/or the base plate; one or more types of filter media are positioned internally and/or externally with respect to the housing; and a separate external handle is optionally secured to the housing. Power is supplied by floating electrical cables attached to an external source, such as a transformer or a battery contained in a floating housing at the surface of the pool; pressurized water can also be provided via a hose for water turbine-powered cleaners. Tank and pool cleaners of the prior art also operate in conjunction with a remote pump and/or filter system which is located outside of the pool and in fluid communication with the cleaner via a hose.
Automated or robotic swimming pool cleaners of the prior art have traditionally been powered by one or more drive motors which, in some instances are reversible; a separate water pump motor is employed to draw debris-containing water through one or more openings in a base plate close to the surface to be cleaned. The water passes through one or more filters positioned in the pool cleaner housing and is typically discharged vertically through one or more ports in an upper surface of the housing to thereby create an opposite force vector in the direction of the surface being cleaned. This configuration of the apparatus and its method of operation permit the movement of the pool cleaner across the bottom wall and optionally, permit it to climb the vertical sidewalls of the pool, while maintaining a firm contact with the surface being cleaned.
An innovative use of water jets to propel a pool cleaner is described in U.S. Pat. No. 6,412,133, the entire disclosure of which is incorporated herein by reference. A single propeller is attached to the drive shaft projecting from the upper end of a vertically-mounted pump motor positioned in the interior of a pool cleaner housing. The water drawn through the base plate and filter(s) is diverted from a direction that is generally normal to the surface being cleaned by means of a directional flap valve and is discharged in alternating directions through a conduit that is positioned along the longitudinal axis of the pool cleaner in the direction of movement of the pool cleaner; the discharge conduit is generally parallel to the surface being cleaned. In one embodiment, the position of the directional flap valve changes when the water pump stops, or is slowed sufficiently, thereby allowing the water jet to be discharged in the opposite direction and causing the pool cleaner to reverse its direction of movement.
Although the water jet reversing propulsion system of U.S. Pat. No. 6,412,133 has been commercially successful, the size and power requirements of the pump motor must account for certain energy losses associated with changing the direction of the flowing water abruptly as it comes into contact with the directional flap valve and undergoes essentially a 90° change in direction.
It would therefore be desirable to provide an apparatus and method that reduced turbulent flow within the interior of the housing and facilitated the alternating directional discharge of the water jets used to propel the apparatus with a minimum loss in energy due to turbulence.
In the description that follows, it will be understood that the cleaner moves on supporting wheels, rollers or tracks, or a combination of these means that are aligned with the longitudinal axis of the cleaner body when it moves in a straight line. References to the front or forward end of the cleaner will be relative to its then-direction of movement.